Plain paper printing apparatus utilizing cathode ray tube devices to form latent electrostatic images on a photoreceptor are known in the art as shown by U.S. Pat. No. 4,134,668 issued on Jan. 16, 1979 in the name of Richard J. Coburn, inventor, a co-inventor of the system described herein. In such a system, the cathode ray tube was used to provide an optical image to effect formation on a traditional photoreceptor of the xerography type, the latent image thereafter being developed and transferred to plain paper and fixed in accordance with the techniques set forth in said patent.
Moreover, it is known in the art to use pin tubes, often referred to as CRT pin tubes, or conductive face-plate cathode ray tubes, sometimes referred to as Braun-tubes or the like which are primarily characterized by the fact that an array of electrodes extend through the face of the cathode ray tube, the electron beam of the cathode ray tube being controlled to selectively impinge upon the pins protruding through the face plate to effect changes in the electric potential of those pins. In U.S. Pat. No. 3,681,527, issued to Messrs. Nishiyama and Tanaka, the use of such a pin tube in connection with a photosensitive belt or the like is disclosed and claimed as a facsimile reading and recording device. The Nishiyama et al patent also discloses an arrangement whereby a reflective beam within the pin tube is varied depending upon the amount of electric charge presented by a belt, the change in electric signal being sensed and collected to be used with a distant facsimile receiver.
A still further work in the electrostatic printing art is found in a publication entitled "High Speed Non-Impact Printer Using Dielectric Drum", attributed to Masakatsu Horie and Hideo Takahashi of Fujitsu Laboratories Limited wherein there is disclosed a drum-type electrostatic printing system. In this Fujitsu system, the drum is provided with a positive polarity precharge, the drum cooperating with an array of pins which are used to selectively discharge portions of the drum to form a latent image, which latent image is thereafter developed and printed. The Fujitsu article discloses a plurality of suitable dielectrics, the principal feature being a plurality of discrete pins placed a small distance from the electrostatic drum, the information being supplied by suitable switching circuits to the pins forming a part of the recording head.
Finally, it is known in the art to use so-called liquid developers of the type shown in U.S. Pat. Nos. 3,892,481 and 3,892,418 as well as U.S. Pat. No. 4,035,071, all of which show systems utilizing liquid developers or toners containing the desired charged particles which are used in connection with the electrostatic charge distribution on a drum to form a latent image which is thereafter transferred and fixed.
It is therefore well-known in the prior art to use electrostatic imaging, liquid toners, and the broad concept of selective discharge of a precharged electrostatic drum to effect formation of latent image charges which can thereafter be developed with liquid toners, transferred and converted into printed intelligence.